Comparative and competitive adsorptive removal of Ni2+ and Cu2+ from aqueous solution using iron oxide-vermiculite composite

Abstract In this study, iron oxide-vermiculite composite (Iovc) with a high specific surface area (SSA) was prepared to remove Ni 2 + and Cu 2 + from aqueous solution. It was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM). The effects of initial pH of the solution, contact time and adsorbent concentration on the adsorption efficiency were investigated systemically. Equilibrium adsorption isotherms were measured for the single component by using various models. The homogenous adsorption of Ni 2 + and Cu 2 + was confirmed in the single system by Langmuir and Koble–Corrigan models. For the binary adsorption of Cu 2 + and Ni 2 + ions have been analyzed by using non-modified Langmuir, modified Langmuir, extended Langmuir, extended Freundlich and Sheindorf–Rebuhn–Sheintuch (SRS) models. The competitive extended Langmuir model described well the competitive adsorption of Ni 2 + and Cu 2 + . Maximum adsorption capacities for Ni 2 + and Cu 2 + in the binary system are 101.3 and 59.7 mg/g, respectively. In the kinetic study, the experimental data fitted well the pseudo-second-order kinetics for Ni 2 + and Cu 2 + adsorption data. Furthermore, calculated thermodynamic parameters, ΔG°, ΔH° and ΔS° of adsorption showed that the adsorption of Ni 2 + and Cu 2 + was feasible, spontaneous and an exothermic process.